使用ninject绑定同一接口的不同实现

Question

I use ninject to inject my dependencies in WPF project with MVVM approach. I have created UserControl that showing data in Grid, and contains a button. On button click every record in Grid is checked by my IChecker implementation injected by Ninject. The problem is, I am using two instances of this UserControl with two instances of ViewModel bound into it's DataContext . I want to pass diffrent implementations of my IChecker to diffrent instances of same type ViewModel . How can I achieve that with Ninject?

Answer 1

You have multiple options, as specified in Ninject Contextual Binding documentation

Ninject WhenXXX

Some out of the box Contextual Bindings available are:

    Bind<IWarrior>().To<Ninja>();
    Bind<IWarrior>().To<Samurai>().WhenClassHas<ClimberNeeded>();
    Bind<IWarrior>().To<Samurai>().WhenTargetHas<ClimberNeeded>();
    Bind<IWarrior>().To<SpecialNinja>().WhenMemberHas<SwimmerNeeded>();
    Bind<IWarrior>().To<Samurai>().WhenInjectedInto(typeof(OnLandAttack));
    Bind<IWarrior>().To<SpecialNinja>().WhenInjectedInto(typeof(AmphibiousAttack));

Or you can provide a predicate and use custom logic wit hthe Target tinfo:

Bind<IWarrior>().To<Samurai>().When(request => request.Target.Member.Name.StartsWith("Climbing"));
Bind<IWarrior>().To<Samurai>().When(request => request.Target.Type.Namespace.StartsWith("Samurais.Climbing"));

Custom Factory

If you're logic starts getting comlex for deciding when to inject what, you may want to implement a some sort of ICheckerFactory which will know which IChecker to create based on some parameters.